This project is concerned with normal and abnormal speech production, mainly from biomechanical and neuromotor perspectives. The three studies elaborated are concerned with respiratory function and are a continuation of thematic research that has been conducted in our laboratory over more than two decades. For the studies proposed, non-invasive methods will be used. Study #1A will longitudinally and cross-sectionally investigate and document the nature of the refinement of speech breathing in young children and provide a data base against which young children with speech breathing disorders can be compared. Study #lB will longitudinally investigate and document the nature of the emergence of speech breathing in infants-children with neuromotor problems associated with cerebral palsy. It will make a direct contribution to our understanding of the salient features of the control problems involved and suggest implications for the evaluation and management of children with neuromotor impairments. Study #1C will investigate the interaction between speech breathing and ventilation in normal adults and provide a data base against which adults with various disorders can be compared. This study will elucidate the mechanisms involved in drive-to-speak versus drive-to-breathe factors and will shed light on how cognitive, chemical, and mechanical factors converge at the speech breathing-ventilation interface.